Dynamo electric machine and method of manufacturing the same

ABSTRACT

Each of a plurality of unit windings  41  is formed by being divided into a first winding section  42  having opened end portions and a second winding section  43 , and the first winding section  42  is shaped in such a manner that a step in radial direction of a stator core  2  is formed between opposing side sections  46  and  47  and the opened end sections are bent in the crossing over direction of the winding so that open ends  443  and  444  of the opened end sections  44  oppose each other in the radial direction of the stator core  2 , then the open ends  443  and  444  are connected by winding conductor pieces  431  and  432  of the second winding section to complete the unit winding  41 , thereby, end sections of a stator winding are shortened and a small size dynamo electric machine is realized.

This application is a division of application Ser. No. 09/943,360, filedAug. 31, 2001, now U.S. Pat. No. 6,791,227.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a dynamo electric machine and a methodof manufacturing the same, and, in particular, relates to a dynamoelectric machine which is suitable for size reduction and a method ofmanufacturing the same.

2. Conventional Art

As, for example, disclosed in JP-A-10-66314 (1998), JP-A-8-298756 (1996)and JP(PCT)-A-10-507057 (1998), a stator winding of a conventionaldynamo electric machine is constituted in such a manner that a pluralityof unit windings are manufactured in advance by molding a windingconductor wound in a plurality of times in a predetermined shape (forexample, a hexagonal shape) and are disposed into a plurality of slotsin a stator core so that each of the unit windings crosses over theplurality of slots. Further, as disclosed in JP-A-6-209535 (1994), eachof a plurality of unit windings which constitutes the stator winding isconstituted by two parts one as an in-slot coil and the other as aninter slot crossover coil.

The above referred to crossing over amount of the unit winding isdetermined based on the number of poles of the stator, therefore, thelength of the end section of the unit winding is determined by themagnitude of the crossing over amount. When the number of poles of thestator is large, the amount of crossing over of the unit windinggenerally decreases, therefore, the length of the end section of theunit winding is shortened in comparison with a stator having a smallnumber of poles. Further, the length of the end section of the unitwinding can be shortened by a certain degree by improving the shape of aportion corresponding to the end section of the unit winding of awinding frame used when winding the winding conductor.

However, when the length of the end section of the unit winding isgreatly shortened, the disposing work of the winding conductor intoslots of the stator core is disturbed. Therefore, the following measureis conceived, in that at the time of disposing the unit winding whilelimiting the length shortening of the end section of the unit winding soas not to disturb the disposing work, the unit winding are disposed intothe slots of the stator core, and after completing the disposing of allof the unit windings the respective sections of the unit windings areforcedly shaped to shorten the same.

However, such manufacturing method requires a large mechanical force toshape the end sections of the unit windings, further, when shaping theend sections of the unit windings, such as an insulating member insertedin the slots of the stator core and an enamel insulative coating appliedover the surface of the winding conductor may be damaged which likelycauses to lower the break down voltage of the stator and to decrease theperformance of the dynamo electric machine concerned. Still further, theamount of the forced shortening of the end sections of the unit windingis limited, therefore, it is impossible to expect a significantshortening of the end section of the unit winding with such measure.

With regard to the above problem, in the former prior art referred toabove, it is impossible to shorten the length of the end section of theunit winding while preventing disturbance at the time of disposing workof the winding conductor, because the unit windings are shaped inadvance. Further, the latter prior art referred to above takes noaccount of the significant shortening of the length of the end sectionsby shaping the end sections of the unit windings.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a size reduced dynamoelectric machine by shortening the end section of the stator winding.

Another object of the present invention is to provide a method ofmanufacturing a dynamo electric machine which can shorten the endsection of the stator winding.

Still another object of the present invention is to provide a dynamoelectric machine of which insulating property can be enhanced and amethod of manufacturing the same.

A further object of the present invention is to provide a dynamoelectric machine of which cooling efficiency at the end section of thestator winding can be enhanced and a method of manufacturing the same.

One of the features of the present invention is that each of a pluralityof unit windings constituting the stator winding is formed by dividingat least two winding sections. More specifically, each of a plurality ofunit windings constituting the stator winding is formed by dividing intoa first winding section of which one of end sections is opened, opposingside sections are shaped so as to form a step in the radial direction ofthe stator core, the open ends of the opened end section face each otherin the radial direction of the stator core and the opened end section isbent in a crossing over direction of the unit winding, and a secondwinding section connecting the open ends of the first winding section.

Herein, the end sections of the unit winding imply portions in the unitwinding which project from the both end portions in axial direction ofthe stator core to the outside in the axial direction of the stator coreand are called sometimes as a coil end portion. The side sections of theunit winding imply portions in the unit winding which are disposed inthe slots of the stator core and are called sometimes as a coil sideportion.

In the present invention, the stator winding is constituted by disposinga plurality of unit windings in a plurality of slots in the stator corein such a manner that one of two side sections of a unit winding isdisposed in a slot other than a slot where the other side section of theunit winding is disposed while crossing over a plurality of slots.Namely, the stator winding is constituted by a so called distributedwinding. In such instance, in the present invention, the stator windingis constituted by repeating the following process by the number of theunit windings.

The first winding section is formed in advance in such a manner that aplurality of winding conductors laminated in a straight shape aretwisted at the midway thereof so that the width between the two sidesections thereof crosses over a plurality of slots, a step is formedbetween the two side sections in the radial direction of the stator coreand straight shaped open ends are formed at one of two end sections.Subsequently, the two open ends of the first winding section areinserted into two slots from one side of both ends in the axialdirection of the stator core. Then, the straight shaped open ends of thefirst winding section which is projected from the other side of bothends in the axial direction of the stator core are bent in the crossingover direction of the unit winding so that the open ends face each otherin the radial direction of the stator core. Finally, the open ends ofthe opened end section of the first winding section are connected by awinding conductor piece constituting the second winding section.

When connecting the opened end section of the first winding section by awinding conductor piece constituting the second winding section, inorder to form a winding conductor having a plurality of turns among atleast two winding conductors constituting the first winding section oneof the open ends of one winding conductor and the other open end of theother winding conductor are connected by fastening therebetween thewinding conductor pieces constituting the second winding section and thesame operation is performed depending on the number of windingconductors in the unit winding. The unit winding is constituted byforming from a lamination of a plurality of flat shaped windingconductors.

As a result, in each of the slots of the stator core, a plurality ofunit windings are disposed in such a manner that unit windings havingdifferent crossing over directions are piled in a slot in its depthdirection, the laminating direction of the winding conductorsconstituting a unit winding is in the latitudinal direction of the slotand a plurality of unit windings are disposed in a slot. At thisinstance, the respective opened end sections of the plurality of unitwindings are formed in such a manner that two portions which projectfrom an end in the axial direction of the stator core to the outside inthe axial direction of the stator core are bent in the crossing overdirection of the unit winding, the two portions bent in the crossingover direction of the unit winding are stepped in the radial directionof the stator core and twisted portions of the two portions bent in thecrossing over direction of the unit winding are extended in the radialdirection of the stator core. Further, the end sections at the oppositesides of the respective opened end sections of the plurality of the unitwindings are shaped in advance when forming the first winding section soas to have the same shape as the opened end sections as explained.

According to the present invention, since the unit winding is dividedinto at least two winding sections, in that divided into the firstwinding section having the opened end sections and the second windingsection for connecting the open ends of the opened end sections of thefirst winding section, a conventional restriction subjected whendisposing a unit winding formed by winding the winding conductor in aplurality of turns (for example, in a hexagonal shape), namely, therestriction that the length of the end section of the unit winding hasto be kept within a length which prevents interference between the unitwindings, is freed.

Moreover, according to the present invention, since the unit winding isconstituted in such a manner that the opened end sections of the firstwinding section of which opposing side sections are stepped in theradial direction of the stator core are bent in the crossing overdirection of the unit winding so as to oppose the opened end sectionseach other in the radial direction of the stator core as well as theopen ends of the opened end sections of the first winding section areconnected by the winding conductor piece constituting the second windingsection, at least the opened end sections of the unit windings areformed in such a manner that two portions which project from the end inthe axial direction of the stator core to the outside in the axialdirection of the stator core are bent in the crossing over direction ofthe unit winding, the two portions bent in the crossing over directionof the unit winding are stepped in the radial direction of the statorcore and twisted portions of the two portions bent in the crossing overdirection of the unit winding are extended in the radial direction ofthe stator core, thereby, the opened end section of the unit winding isshortened by the amount of the twisted portion of the two bent portionsin the crossing over direction of the unit winding.

Accordingly, in the present invention, the length of the respective endsections of a plurality of unit windings can be greatly shortened.Further, since the end sections of the respective closed end sections ofthe plurality of unit windings are formed in the same shape as those ofthe opened end sections, the length of the respective end sections ofthe plurality of the unit windings can be further shortened.

Further, according to the present invention, when shaping the endsections of the first winding section disposed in the slots of thestator core in a predetermined shape, the shaping is performed under acondition that the end section of the first winding section is opened,therefore, no large mechanical force is required therefor, therefore, apossibility of damaging the insulating member inserted in the slots ofthe stator core and the insulative coating applied over the surface ofthe winding conductors is small.

Still further, according to the present invention, since the respectiveend sections of the plurality of the unit windings are formed andarranged orderly in such a manner that two portions which project fromthe end in the axial direction of the stator core to the outside in theaxial direction of the stator core are bent in the crossing overdirection of the unit winding, the two portions bent in the crossingover direction of the unit winding are stepped in the radial directionof the stator core and twisted portions of the two portions bent in thecrossing over direction of the unit winding are extended in the radialdirection of the stator core, a ventilation resistance to cooling windcan be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a structure of a unit windingconstituting a stator winding representing an embodiment of the presentinvention;

FIGS. 2(a), 2(b) and 2(c) are exploded views of a first winding sectionin the unit winding of FIG. 1, wherein FIG. 2(a) shows a structure of awinding conductor corresponding to a first turn of the unit winding,FIG. 2(b) shows a structure of a winding conductor corresponding to asecond turn of the unit winding, and FIG. 2(c) shows a structure of awinding conductor corresponding to a third turn of the unit winding;

FIG. 3 is a cross sectional view showing a structure of a dynamoelectric machine representing an embodiment of the present invention;

FIG. 4 is a cross sectional view taken along arrowed line IV—IV in FIG.3;

FIG. 5 is a perspective view seen along the arrowed direction V in FIG.3 and shows a structure of one of the end sections of the stator windingat one side thereof;

FIG. 6 is a perspective view seen along the arrowed direction VI in FIG.3 and shows a structure of one of the end sections of the stator windingat the other side thereof; and

FIG. 7 is a cross sectional view seen along the arrowed direction VII inFIG. 3 and shows a structure of a connection ring.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will be explained with referenceto FIGS. 1 through 7. In the drawings 1 is a stator. The stator 1comprises a stator core 2 and a stator winging (or “a stator coil”). Thestator core 2 is a cylindrical shape formed by laminating a plurality ofsilicon steel sheets. Along the inner circumference of the stator core 2a plurality of slots (or grooves) are formed which continuously extendin the axial direction as well as each has an opening portion 3 a formedat the inner circumferential surface of the stator core 2.

In each of the slots 3 a unit winding (or “unit coil”) 41 is disposedvia a slot liner 3 b, which is an insulating member for insulatingbetween the stator core 2 and the unit winding 41. Respective windingsides of a unit winding 41 are disposed in separate two predeterminedslots so as to cross over a predetermined number of slots (in thepresent embodiment two slots are crossed over). Namely, the presentEmbodiment employs a distributed winding for the stator winding 4.

Respective unit windings 41 project from both end portions in the axialdirection of the stator core 2 to the outside in the axial direction ofthe stator core 2 as shown in FIGS. 5 and 6. In each of the slots 3 unitwindings 41 having different crossing over directions are disposed whilebeing piled in the depth direction (radial direction of the stator core2) of the slot 3. One ends of the respective end portions of the unitwindings 41 are connected for every U phase, V phase and W phase via aconnecting ring 5 so as to constitute an electrical circuit for threephase Y connection.

The connecting ring 5 is integrally molded by inserting crossing overlines 51 and 52 into a heat resistant resin. The cross over lines 51 arefor forming respective phases of U phase, V phase and W phase byconnecting the end portions of two winding conductors. The crossing overline 52 is for forming a Y connection of the respective phases of Uphase, V phase and W phase by connecting the last terminals of the unitwindings for the respective phases. With this crossing over line 52 aneutral point is formed. The stator winding 4 is constituted byelectrically connecting via the connecting ring 5 one ends of the unitwindings disposed in the respective slots 3 so as to constitute anelectric circuit of three phase Y connection.

Herein, the end sections of the unit winding 41 imply portions in theunit winding 41 which project from the both end portions in axialdirection of the stator core 2 to the outside in the axial direction ofthe stator core 2 and are called sometimes as a coil end portion. Theside sections of the unit winding 41 imply portions in the unit winding41 which are disposed in the slots 3 of the stator core 2 and are calledsometimes as a coil side portion.

In the inner circumferential side of the stator 1, a rotor of whichillustration is omitted is disposed via a predetermined gap andsupported by a bearing so as to permit rotation thereof. The structureof the rotor varies depending on kinds of dynamo electric machines. Forexample, an induction motor used for driving an electric car, a hybridcar and a fork lift uses a rotor in which a rotor winding constituted byaluminum or copper made conductor is disposed in a rotor core. Further,a synchronous motor likely applied for the above uses a rotor in which apermanent magnets are buried inside a rotor core or are provided on theouter circumferential surface of a rotor core. Further, a generatorwhich is used for charging a battery mounted on a vehicle or forsupplying power for a vehicle mounted load uses a rotor in which a rotorwinding is disposed on the rotor core as well as permanent magnets arecaught between claw shaped poles.

Now, the structure of the stator winding 4 of the present embodimentwill be explained specifically. As has been explained above, the statorwinding 4 is constituted by the unit windings 41 disposed in therespective slots. For the formation of the respective unit windings 41 aflat plate shaped winding conductor (or “coil conductor”), so calledflat rectangular wire is used. In the present embodiment each of theunit windings 41 is formed by being divided into two winding sections bymaking use of the flat plate shaped winding conductor and finally (afterbeing disposed in respective slots) a winding conductor having aplurality of turns is formed.

As shown in FIG. 1, the unit winding 41 is formed by being divided intoa first winding section 42 and a second winding section 43. The firstwinding section 42 is formed by laminating a plurality of windingconductors and is constituted by an opened end section 44, a closed endsection 45 and side sections 46 and 47 extending in straight shape. Inthe present embodiment, as shown in FIGS. 2(a) thorough 2(c), the firstwinding section 42 is formed by laminating three winding conductors.FIG. 2(a) shows a structure of a winding conductor corresponding to afirst turn in the unit winding 41 before inserting the same into a slot,FIG. 2(b) shows a structure of a winding conductor corresponding to asecond turn in the unit winding 41 before inserting the same into aslot, and FIG. 2(c) shows a structure of a winding conductorcorresponding to a third turn in the unit winding 41 before insertingthe same into a slot.

Between the side sections 46 and 47 a step (a step nearly correspondingto the width size (the latitudinal size) of the flat rectangular wire)in radial direction of the stator core 2 is given. Thereby, when theunit winding 41 is disposed within slots 3, the side section 46 isarranged at the side of opening portion 3 a in a slot 3 and the sidesection 47 is arranged at the bottom side (the opposite side from theopening portion 3 a) in another slot 3.

The closed end section 45 is continuously formed by inclined sections451 and 452 which are bent in the crossing over direction of the windingand a twisted section 453 which connects the end portions of theinclined sections 451 and 452 as well as extends in the radial directionof the stator core 2. Namely, the closed end section 45 is formed insuch a manner that two portions thereof which project from the endportion in the axial direction of the stator core 2 to the outside inthe axial direction of the stator core 2 are bent in the crossing overdirection of the winding, a step in radial direction of the stator core2 is formed between the two portions bent in the crossing over directionof the winding and the twisted section between the two portions bent inthe crossing over direction of the winding extends in the radialdirection of the stator core 2. Accordingly, when seen the closed endsection 45 from the top thereof the shape of the closed end section 45looks like one side of a hexagonal shape.

The opened end section 44 is formed by the inclined portions 441 and 442bent in the crossing over direction of the winding. Open ends 443 and444 are formed for the inclined portions 441 and 442. The open ends 443and 444 face in the radial direction of the stator core 2 and therespective lengths thereof are different for every winding conductor.Namely, the open end 443 of the winding conductor corresponding to thefirst turn forms one side of lead-out portion of a unit winding 41 andthe open end 444 forms a connecting portion with the open end 443 of thewinding conductor corresponding to the second turn. The open end 444 ofthe winding conductor corresponding to the second turn forms aconnecting portion with the open end 443 of the winding conductorcorresponding to the third turn and the open end 444 thereof forms theother side of lead-out portion of the unit winding 41. Accordingly, asshown in FIGS. 2(a) through 2(c), lengths of respective windingconductors constituting the first winding section 42 are different.

The second winding section 43 is for connecting between the open ends443 and 444 of the first winding section 42 and is constituted by twopieces of winding conductors. The winding conductor pieces 431 connectsthe open end 444 of the winding conductor corresponding to the firstturn with the open end 443 of the winding conductor corresponding to thesecond turn. The winding conductor piece 432 connects the open end 444of the winding conductor corresponding to the second turn with the openend of the winding conductor corresponding to the third turn. With thisconnection, the open ends 443 and 444 of the opened end section 44 ofthe first winding section 42 is closed and a unit winding 41 havingthree turn winding conductors is formed. Further, when seen the openedend section 44 of the first winding section 42 from the top, it lookslike the other end portion of the hexagonal shape.

Now, a method of manufacturing the dynamo electric machine of thepresent embodiment, in particular, a manufacturing process of the statorwinding 4 will be explained. At first, straight shaped lamination bodywhich is formed by laminating three flat rectangular straight shapedcopper wires applied with enamel insulative coating is twisted at themidway thereof around an axis in the latitudinal direction on a planeperpendicular to the lamination plane and a step (a step in the radialdirection of the stator core 2) substantially corresponding to the widthsize (latitudinal side) of the flat rectangular wires is formed betweenthe two side sections with reference to the twisted center.Subsequently, the side of the twisted portion of the lamination body isshaped by making use of a shaping jig not shown so that a crossing overwidth crossing over two slots is formed between the two side sections,namely so that the side sections 46 and 47, the inclined portions 451and 452 and the twisted portion 453 of the closed end section 45 areformed. Through thus shaping as shown in FIGS. 2(a) through 2(c) thefirst winding section 42 having different lengths for every windingconductor and having a straight shaped opened end section 44 is formed.

Then, the straight shaped end sections 44 of the first winding section42 are inserted from one of two ends in the axial direction of thestator core 2 into two slots 3 where the slot liner 3 b is disposed. Atthis instance, the side section 46 of the first winding section 42 isarranged at the side of the opening portion 3 a in a slot 3 and the sidesection 47 is arranged at the bottom side (the opposite side of theopening portion 3 a) in another slot 3. Thereafter, the straight shapedend sections 44 of the first winding section 42 which project from theother side of the both ends in the axial direction of the stator core 2are bent in the crossing over direction by making use of a shaping jigso that the open ends 443 and 444 face each other in the radialdirection of the stator core 2. Through thus shaping, the first windingsection 42 having the opened end section 44 including the inclinedportions 441 and 442 is formed.

Subsequently, the winding conductor piece 431 constituting the secondwinding section 43 is inserted between the open end 444 of the windingconductor corresponding to the first turn and the open end 443 of thewinding conductor corresponding to the second turn and connects betweenthe both ends through a butt contact. Further, the winding conductorpiece 432 constituting the second winding section 43 is inserted betweenthe open end 444 of the winding conductor corresponding to the secondturn and the open end 443 of the winding conductor corresponding to thethird turn and connects between the both ends through a butt contact.Through the connection, the open ends 443 and 444 of the opened endsection 44 of the first winding section 42 are closed and a unit winding41 having the winding conductors of three turns is formed. Further, theconnection between the open ends 443 and 44 of the opened end section 44of the first winding section 42 with the winding conductor pieces 443and 444 is performed with TIG welding. Further, for the connection ofthe respective open ends with the winding conductor pieces the enamelinsulative coating applied at the connection portions is removed inadvance.

Through repeating the above series of processes by the number of unitwindings 41 to be disposed in the respective slots 3, in each of theslots 3 two unit windings 41 crossing over two slots 3 and in differentcrossing over direction are disposed in a laminated manner in its depthdirection (in radial direction of the stator core 2).

Then, the respective end portions 44 of the unit windings 41 areconnected via the connecting ring 5 for every U phase, V phase and Wphase so as to constitute an electric circuit of three phase Yconnection. More specifically, respective end portions of the adjacenttwo unit windings 41 are connected via the crossing over line 51 of theconnecting ring 5, in that between one of the lead-out portions formedat the end portion 44 for one unit winding (the open end 443 of thewinding conductor corresponding to the first turn of the unit winding41) and the other lead-out portion formed at the end portion 44 for theother unit winding (the open end 444 of the winding conductorcorresponding to the third turn of the unit winding). In other words,for every two slots 3, the lead-out portion of the end section 44 of aunit winding 41 arranged at the side of the opening portion 3 a in oneof two slots 3 (the open end 443 of the winding conductor correspondingto the first turn of the unit winding 41) and the lead-out portion ofthe end section 44 of another unit winding 41 arranged at the bottomside (the opposite side from the opening portion 3 a) of the other slots3 (the open end 444 of the winding conductor corresponding to the thirdturn of the unit winding 41) are connected via the crossing over line 51of the connecting ring 5. Through repeating such connection by thenumber of the unit windings 41, the respective U, V and W phases areformed.

Subsequently, final ends of the unit windings 41 for the respective U, Vand W phases are connected by the crossing over line 52 of theconnecting ring 5. Through this connection an electric circuit of threephase Y connection is constituted and the stator winding 4 is completed.The connection between the respective crossing over lines 52 of theconnecting ring 5 and the end sections of the unit windings 41 isperformed through TIG welding. Further, for the connection of thecrossing over lines 51 and 52 of the connecting ring 5 and the lead-outportions of the end sections of the unit windings 41 the enamelinsulative coating applied at the connecting portions of the endsections 44 of the unit windings 41 is removed in advance.

According to the present embodiment as has been explained hitherto,since each of the unit windings 41 is divided into the first windingsection 42 including the opened end section 44 and the second windingsection 43 which connects between the open ends 443 and 444 of theopened end section 44 of the first winding section 42, a conventionalrestriction subjected when disposing a unit winding formed by windingthe winding conductor in a plurality of turns (for example, in ahexagonal shape), namely, the restriction that the length of the endsection of the unit winding has to be kept within a length whichprevents interference between the unit windings is freed.

Moreover, according to the present embodiment, since the unit winding 41is constituted in such a manner that the opened end sections 44 of thefirst winding section 42 are bent in the crossing over direction so thatthe open ends 443 and 444 of the opened end section 44 of the firstwinding section 42 which is shaped so that a step in the radialdirection of the stator core 2 is formed between the opposing sidesections 46 and 47 oppose each other in the radial direction of thestator core 2 as well as the open ends 443 and 444 of the opened endsection 44 of the first winding section 42 are connected by the windingconductor pieces 431 and 432 constituting the second winding section 43,one side of the end sections of the unit winding (at the opened endsection 44 of the first winding section 42) is shaped in such a mannerthat the two portions which project from the end portion in axialdirection of the stator core 2 to the outside in the axial direction ofthe stator core 2 are bent in the crossing over direction of thewinding, a step in radial direction of the stator core 2 is formedbetween the two portions bent in the crossing direction and the twistedportion between the two portions bent in the crossing over direction ofthe winding extends in the radial direction of the stator core 2,thereby, the length of the one side of the end sections of the unitwinding 41 is determined by the distance from the end portion in theaxial direction of the stator core 2 to the open ends 443 and 444 of theinclined portions 441 and 442 of the opened end section 44 of the firstwinding section 42, the length corresponding to the twisted portionsbetween two portions bent in the crossing over direction, namely, theportion corresponding to the second winding section 43, is shortened.

Therefore, according to the present embodiment, the length of therespective end sections of the unit windings 41 can be shortened, thesize in the axial direction of the dynamo electric machine can bereduced, thereby, the size of the dynamo electric machine can bereduced. Further, according to the present embodiment, since the otherside of the respective end sections of the unit windings 41 (the closedend sections of the first winding sections) is likely shaped to assumethe same configuration as the one side of the respective end sections ofthe unit windings, like the one side of the respective end sections ofthe unit windings the other side of the respective end sections of theunit windings can be shortened by the amount corresponding to thetwisted portion 453, thereby, the size of the dynamo electric machinecan be further reduced. According to the present embodiment, the lengthof the respective end sections of the unit windings can be reduced about½ of the conventional one, a significant size reduction and light weightof a dynamo electric machine can be achieved. Such dynamo electricmachine is effective for an electric vehicle such as an electric car, ahybrid car and a battery type fork lift. Of course, the present dynamoelectric machine is effective for a vehicle such as an ordinary gasolinecar for enhancing fuel economy.

Further, according to the present embodiment, when shaping the openedend sections 44 of the first winding section 42 which is disposed in therespective slots 3 into a predetermined shape, the shaping into thepredetermined shape is performed under a condition that the opened endsection 44 of the first winding section 42 is opened, no largemechanical force is required for the shaping, therefore, a possibilityof damaging the slot liners 3 b inserted in the respective slots 3 andthe enamel insulative coating applied over the surface of the windingconductors is small. As a result, according to the present embodiment,the insulating property of the dynamo electric machine can be enhancedas well as reliability of the dynamo electric machine can be enhanced.

Still further, according to the present embodiment, since the respectiveend sections of the unit windings 41 which are disposed in therespective slots 3 are shaped and arranged orderly in such a manner thatthe two portions which project from the end portion in the axialdirection of the stator core 2 to the outside in the axial direction ofthe stator core 2 are bent in the crossing over direction of thewinding, a step in the radial direction of the stator core 2 is formedbetween the two portions bent in the crossing over direction of thewinding and the twisted portion between the two portions bent in thecrossing over direction of the winding extends in the radial directionof the stator core 2, the ventilation resistance for cooling wind can bereduced. Moreover, through the use of the flat rectangular wires suchadvantage can be further enhanced. Therefore, according to the presentembodiment, a cooling efficiency of the stator winding 4 can be enhancedand an enhanced output capacity of a dynamo electric machine can beachieved or alternatively further size reduction of the dynamo electricmachine can be achieved. The present dynamo electric machine iseffective for an electric vehicle requiring a high output capacity suchas an electric car, a hybrid car and a battery type fork lift. Further,the present dynamo electric machine is effective for enhancing outputcapacity for a four wheel drive car using a motor.

Still further, according to the present invention, when disposing therespective unit windings 41 into the slots 3, the first winding section42 constituting the unit winding 41 is inserted from one of the two endportions in the axial direction of the stator core 2, the openingportion 3 a of the slot 3 is subjected to no restriction with regard tomanufacturing method. Conventionally, since the unit winding is insertedfrom the opening portion of the slot, the size of the opening (thecircumferential width of the opening portion in the stator core) wasdetermined depending on the diameter of the unit winding and theworkability therewith, moreover, the size was larger than that requiredin view of the performance. However, according to the presentembodiment, the first winding section 42 constituting the unit winding41 is inserted from one of the two end portions in the axial directionof the stator core 2, the opening portion 3 a of the slot 3 is neversubjected to a requirement with regard to manufacturing method and thesize of the opening portion 3 a of the slot 3 can be set at an optimumsize in view of the performance of the dynamo electric machine.Therefore, according to the present embodiment the performance of thedynamo electric machine can be enhanced.

Still further, according to the present embodiment, since the length ofthe end sections of the stator winding 4 has been shortened as has beenexplained above, such as resistance and reactance of the stator winding4 can be reduced. Therefore, the present embodiment is suitable for adynamo electric machine meeting a specification of a large current and alow voltage.

According to the present invention, since the length of the respectiveend sections of a plurality of unit windings can be shortenedsignificantly, the end sections of the stator winding can be shortenedand the size of a dynamo electric machine can be reduced. Further, amethod of a manufacturing a dynamo electric machine which can shortenthe end sections of the stator winding can be produced. Further,according to the present invention, since a possibility of damaging aninsulating member inserted in the slots of the stator core and aninsulative coating applied over the surface of the winding conductors issmall, an insulating property of a dynamo electric machine can beenhanced. Further, a method of manufacturing a dynamo electric machinewhich can enhance the insulating property of the dynamo electric can beprovided. Still further, according to the present invention since aventilation resistance for cooling wind at respective end sections of aplurality of unit windings can be reduced, cooling efficiency at the endsections of the stator winding can be enhanced. Further, a method ofmanufacturing a dynamo electric machine which can enhance coolingefficiency at the end sections of the stator winding can be provided.

1. A method of manufacturing a dynamo electric machine in which one ofside sections of each of a plurality of unit windings is disposed in oneof a plurality of slots formed on a stator core other than another slotin which the other side section thereof is disposed by crossing over apredetermined plurality of slots wherein a first winding section of theunit winding having a straight shaped open end sections at the one sidethereof is formed in advance in such a manner that a laminate of aplurality of straight shaped winding conductors is twisted at the midwaythereof to form a crossing over width between two side sections formedwhich permits to cross over a plurality of slots as well as to form astep in the radial direction of the stator core between the two sidesections, two open ends of opened end sections of the first windingsection are inserted into two of the plurality of slots from one of twoends in the axial direction of the stator core, the straight shapeopened end sections of the first winding section which project from theother end portion in the axial direction of the stator core are bent inthe crossing over direction of the winding so as to oppose the open endsin the radial direction of the stator core, the open ends of the openedend sections of the first winding section are connected by a windingconductor piece constituting a second winding section of the unitwinding, and above series of steps is repeated by the number of unitwindings to be disposed in the plurality of slots so as to constitute astator winding.
 2. A method of manufacturing the dynamo electric machineof claim 1, wherein the unit windings having different crossing overdirections are disposed and laminated in each of the plurality of slotsin its depth direction.
 3. A method of manufacturing the dynamo electricmachine of claim 1, wherein each of the plurality of unit windings isformed by laminating a plurality of flat plate shaped windingconductors.
 4. A method of manufacturing the dynamo electric machine ofclaim 1, wherein each of the plurality of unit windings is disposed inone of the slots in such a manner that the laminating direction of thewinding conductors coincides with the latitudinal direction of the slot.5. A method of manufacturing the dynamo electric machine of claim 1,wherein each of the plurality of unit windings is constituted in such amanner that among at least two winding conductors constituting the firstwinding section one open end of one winding conductor and other open endof the other winding conductor are connected by inserting a windingconductor piece constituting the second winding section so that windingconductors having a plurality of turns are formed.
 6. A method ofmanufacturing the dynamo electric machine of claim 1, wherein each ofthe plurality of unit windings is shaped in such a manner that the endsection opposite from the opened end section has substantially the sameshape as the opened end section.